Since occurrences of “911” event and anthrax event from 2001, anthrax biological attack events via email continuously took place in America and other countries and regions. There has been verified with 17 infection cases, in which many people died. Those infected people have been proven to be infected by contacting mails or packages carrying anthrax bacilli.
Many countries devote much manpower and funds to undertake researches on detection and sterilization of certain bacteria. However, conventional chemical sterilization cannot exterminate anthrax bacilli and take long time with low efficiency, and it cannot meet the needs for detection, quarantine and sterilization of anthrax bacilli for departments with mails of collective disposition and large disposal output. Methods such as microwave, laser or high temperature steam etc. may bring unrecoverable damages to the mails. And plasma electrical discharge method, or low energy electron beam (hundreds of keVs) radiation method can only illuminate anthrax bacilli etc on surfaces of mails or in thin mails, and can not kill anthrax bacilli etc. carried in mails with relative thicknesses. It is a most preferable solution which achieves high speed sterilization for items in mails etc. by high energy electron beam radiation processing.
Sterilization and antisepsis can be achieved by radiation processing with high energy accelerator. The required radiation dose is 25 kGy in a detection standard of medical appliance sterilization. It is pointed out in formal documents of WHO that the kill dosage range for radiation sterilizing spore type bacilli is 10-50 kGy and the kill dosage range for non-spore type bacilli is 0.5-10 kGy. And it is an efficient sterilizing technical solution by using high energy electron beam up to 25 kGy dosage to effectively eliminate different kinds of bacilli including anthrax spore therein.
An electron beam radiating sterilization apparatus generally includes a power supply such as a modulator, an accelerating tube, a beam flow extraction device such as a scanning box, an article transporting system and a control system etc. High energy electron beam radiation sterilization apparatuses have been developed by many organizations with energy range of 2-9 MeV, including “Betaline” developed by IBA corporation, Belgium, “Surebeam” by Titan corporation, USA, “SML5520” by NUCTECH corporation, PRC, etc. These apparatuses have huge volume with heavy weights up to tens of tons, and they need fixed operation sites, some of them even need certain radiation shielding constructions.
The electron beam radiation sterilization safety apparatus are mainly used for preventive sterilization, ensuring no damage to personnel and sites by mails and documents. And existing or potential clients thereof are chief departments at home and aboard. The safety of the chief departments at home have far-reaching political and social influences, since banks (currency sterilization), hospitals (medical wastes and sewage), postage systems hold indispensable functions for daily life and national economy.
In the chief departments of many countries, it is difficult to build huge volume radiation shielding constructions. In addition, many important conferences and activities etc. have no fixed sites, and there are also needs for rapid and complete sterilization by a maneuverable, flexible electron beam radiation sterilization apparatus, which does not require an additional construction, radiating every kind of documents, mails etc. to achieve the safety purpose.